Cellulose ethers have been used commercially in a variety of applications. Typical industrial applications for cellulose ethers include, for example, use as viscosity adjusters, suspension aids, oil field drilling and fracturing materials, adhesion promoters for siliceous substrates, e.g., glass panels and ceramics, coating materials for plastic and metal substrates, protective colloids and building materials, e.g., wallboard compound and latex grout additive. Typical personal care applications include, for example, pharmaceutical and cosmetic compositions, e.g., ointments, skin creams, lotions, soaps, shampoos, conditioners and the like.
One predominant use for cellulose ethers is in the latex industry where the cellulose ethers are utilized as thickeners. In latex paint, cellulose ethers generally provide excellent thickening efficiency and other properties while being substantially inert to the latexes, surfactants and coalescing agents commonly used in latex paints.
Cellulose ethers, such as for example, hydroxyethyl cellulose, are generally sold as dry powders. The final compositions which comprise the cellulose ethers are often liquids. The dry powdered cellulose ethers are typically incorporated into the final liquid compositions by the formulators of the liquid products. In general, solids are more difficult to measure, dissolve, transfer and store than liquids. In contrast, liquids generally dissolve more smoothly and are easier to transfer, i.e., can be pumped, than solids.
Aqueous slurries of cellulose ethers have been proposed whereby high concentrations of salt,. e.g., sodium formate, potassium carbonate or diammonium phosphate, are used to sufficiently reduce the water solubility of the cellulose ether to provide a suspension of cellulose ether particles in the carrier. However, such salt-containing slurries have not achieved widespread use in the latex industry, particularly the latex paint industry because the high salt concentration in the slurry is deleterious to the final dried paint film as the salt impairs the weatherability, adhesion and water resistance of the coating.
Accordingly, improved cellulose ether slurries are desired which do not require the use of high concentrations of salt in order to disperse the cellulose ether. In addition, it is desired that the slurries provide high concentrations, e.g., greater than 30 weight percent, of the cellulose ether. It is further desired that the other ingredients in the slurry, e.g., the carrier, be compatible and beneficial to the final composition in which the slurry is employed.